Senior Product Engineer · React / TypeScript · AI Applications

Hello, I'm Brian

Brian Shimkus, Senior Product Engineer

Senior product and front-end engineer with 13 years delivering customer-facing software, integrations, and regulated financial workflows. Extending that background into applied AI with a shipped RAG assistant and ticket classifier, and a documentation assistant and run-inspection tool in progress.

Available for product engineering roles · Chicago, IL · Remote OK

Latest Writing

Blog

Deep dives into building AI applications, enterprise integrations, and customer-facing products. From architecture decisions to production deployment.

Where I've Been

Experience

Independent Product Engineer

Dec 2025 – Present

Insolla (Consulting and portfolio development) · Chicago, IL

  • ›Delivered an automated content pipeline that cut a business owner’s weekly workflow from 8 hours to 10 minutes.
  • ›Built and deployed Salesforce Intelligence, a live RAG assistant over CRM data.
  • ›Built Ticket Triage, comparing keyword rules with structured OpenAI outputs across labeled development and holdout examples.
  • ›Building Ask TanStack Query, a source-grounded documentation assistant in Python, FastAPI, pgvector, and Next.js.
  • ›Building Run Explorer, an accessible run-inspection dashboard in React and TypeScript.

Lead Front-End Developer

Aug 2025 – Dec 2025

TerraFort (Freelance)

  • ›Led design and development of an early-stage web and mobile platform from concept through delivery.
  • ›Owned vendor evaluations and scoped third-party and AI integrations with UX, product, and backend teams.

Senior Front-End Developer

Jul 2024 – Jun 2025

OCC (Contract) · Chicago, IL

  • ›Ran weekly stakeholder sessions at a systemically important financial market utility, aligning goals, demonstrating progress, and resolving questions across workstreams.
  • ›Delivered React and TypeScript solutions from Figma through testing, QA, and production.
  • ›Implemented Mock Service Worker to unblock front-end development from backend dependencies.

Lead Front-End Developer

Oct 2020 – Jan 2024

Marex · Chicago, IL

  • ›Led digitization of broker and trader onboarding, replacing a compliance-heavy paper workflow with an end-to-end digital process.
  • ›Partnered with compliance, operations, and trading teams to scope rollouts and support adoption.
  • ›Integrated the DocuSign API across products to support digital document signing.
  • ›Led a five-person front-end team and designed and ran the team’s internship program.

Earlier Experience

  • Senior Front-End Developer · Walker & Dunlop (Contract)2020
  • Senior Front-End Developer · ICF2019 – 2020
  • Front-End Developer · TransUnion2018 – 2019
  • UX Architect & Front-End Developer · R1 RCM2016 – 2018
  • Front-End Developer · TimeZoneOne (Contract)2015 – 2016
  • Junior Front-End Developer · Kohactive2013 – 2015

What I Know

Skills

AI Applications & Retrieval

  • RAG
  • Embeddings
  • Vector search
  • Source-grounded answers
  • LLM evaluation

Python & Backend

  • Python
  • FastAPI
  • PostgreSQL
  • pgvector

Integrations & Automation

  • REST APIs
  • Webhooks
  • Salesforce
  • DocuSign API
  • OAuth 2.0/JWT
  • Workflow automation

Cloud Deployment

  • Python/FastAPI
  • PostgreSQL/pgvector
  • TypeScript/React apps

Customer Discovery & Delivery

  • Requirements discovery
  • Workflow mapping
  • Solution design
  • Technical demonstrations
  • Stakeholder alignment
  • Technical handoffs

Front-End Development

  • TypeScript
  • React
  • Accessible interfaces

On My Bookshelf

Currently Reading

AI Engineering: Building Applications with Foundation Models

Chip Huyen

A guide to building real applications on top of foundation models.

Mastering Technical Sales: The Sales Engineer's Handbook

John Care and Aron Bohlig

A handbook on technical sales and the role of the sales engineer.

What People Say

Testimonials

Brian and I worked together on the User Experience team, where he was brought in to assist with front end development of our UIUX projects. He did a great job of quickly jumping in to the mix to work on several of our internal projects, bringing a willingness to learn and a positive attitude to every project. He is also very eager to suggest new approaches to projects and brings an innovative, forward-thinking mindset. He is a talented, energetic and very enthusiastic developer and would be a great asset to any team.

Mark Coleman

User Experience Team Colleague

Brian is a hard working & focused user interface and user experience developer. In our time working together at R1, Brian was consistently dedicated and focused on complex projects, often times putting in significant extra work to help the team meet deadlines. He worked equally well with local teams in the office as well as teams based in India. Good teammate that will help you bring your UI/UX to the next level.

Shane Colley

Colleague, R1 RCM

From LinkedIn, earlier in my front-end engineering career.